1. Field of the Invention
The present invention relates to an operation switch used in an audio reproducing device, an air conditioner or the like which are disposed within a vehicle.
2. Description of the Related Art
As an example, the operation switch for the air conditioner is classified into the following three systems.
As shown in FIG. 6, the first system is arranged in a manner that push-type switch knobs 100, 101, 102, 103, 104 and 105 each having a display portion M and an indicator N are disposed in correspondence with a plurality of function portions, respectively. In this system, the display portions M are disposed above switch elements (not shown) for selecting the function portions, respectively. When one of the switch knobs 100 etc. is pushed, the corresponding indicator N is lightened so as to make an operator possible to determine whether or not the corresponding function is operated or not. An air flow rate is adjusted by a not-shown switch knob.
As shown in FIG. 7, the second system is arranged in a manner so as to select the functions (modes) and adjust an air flow rate that there are disposed a display portion 110 for selectively displaying a plurality of functions and two switch knobs, that is, a push-type switch knob 111 for switching the modes and a seesaw type switch knob 112 for adjusting an air flow rate, in the example of this figure. Thus, in this system, the display content of the display portion 110 changes every time the push-type switch knob 111 is pushed. For example, every time the push-type switch knob 111 is pushed, the displayed content changes in an order of 1.fwdarw.2.fwdarw.3.fwdarw.4.fwdarw.1. Further, when the right side or the left side of the seesaw type switch knob 112 is pushed, the corresponding one of plural indicators N1, N2 and N3 provided at the upper portion of the seesaw type switch knob is lightened.
As shown in FIG. 8, the third system is arranged in a manner that there are disposed a display portion 120 for selectively displaying a plurality of functions and an air flow rate, a push-type switch knob 121 for switching modes and a seesaw type switch knob 122 for adjusting an air flow rate. Thus, in this system, the display content of the display portion 120 changes every time the corresponding one of the switch knobs is pushed. To be more concrete, in this system, the display content 120a of the display portion 120 changes every time the push-type switch knob 121 is pushed, whilst when the right side or the left side of the seesaw type switch knob 122 is pushed, the adjusted air flow rate is displayed.
However, each of the aforesaid systems has the following problems.
In the first system, since the switch knobs each having the display portion corresponding to the associated one of the functions are required to be provided for the respective functions, the area occupied by the switch knobs becomes large at the time of arranging them. Thus, the sizes of the respective switch knobs are likely restricted. As a result, there arises a problem that the operability of the operation switch is degraded in the case where the sizes of the respective switch knobs are required to be small in accordance with the increase of the functions, for example.
In each of the second and third systems, since the display portion is required to be provided separately from the switch knobs, there arises a problem that the operation switch requires a large space due to the provision of the space for the display portions.